FIG. 9 is a block diagram showing one example of a configuration of the existing mobile communication system, and the mobile communication system shown in FIG. 9 comprises, as the subscriber side equipment, for example, subscriber data communication terminals (each of which will be referred to hereinafter as a PC) such as personal computers (PCs) 101a and 101b, a mobile communication terminal 102a connected to the PC 101a and designed to make communications with a station side through the use of a radio interface, and an SU (Subscriber Unit) 102b connected to the PC 101b and designed to make communications through an outside antenna 102c with a station side through the use of a radio interface.
Incidentally, although not shown in FIG. 9, a plurality of mobile communication terminals 102a exist therein. Moreover, the mobile communication terminal 102a is called an MS (Mobile Station) in the cellular system. Still moreover, in the case of the WLL system, means corresponding to the mobile communication terminal 102a is called an FWT (Fixed Wireless Terminal). In the following description, for convenience only, these will collectively be referred to simply as “MS 102a”. 
On the other hand, as the station side equipment, there are base stations (BTSs: base station transmission subsystems) 103, a base station control unit (BSC) 104, a packet data distribution serving node (PDSN) 105 functioning as a packet processing unit connected to the internet 107, and an ordinary subscriber exchange (LE), mobile subscriber exchange and others functioning as a general speech processing unit 106 connected to a telephone network 108.
In this configuration, each of the BTSs 103 makes communications through a radio interface with the MS 102a (or the SU 102b), and the BSC 104 controls a plurality of BTSs 103 to carry out the call processing for making the interface on the transmission/reception of IP (Internet Protocol) packet data (which will hereinafter be referred to simply as a “packet”) or voice data between the BTS 103 and the PDSN 105 or the speech processing unit (LE/MSC) 106. In the following description, the BTS 103 and the BSC 104 will sometimes be referred to simply as a “BS 134”.
Moreover, the PDSN 105 carries out the interface in packet transmission/reception between the BSC 104 and the internet 107 and further terminates the point-to-point protocol (PPP) with respect to the PC 101a (or 101b). In this connection, for the user authentication in establishing a PPP link (which is equally referred to as PPP connection) with respect to the MS 102a, this PDSN 105 further carries out the interface with an authentication server 171 in an internet service provider (which will be referred to as an ISP) 170.
With the above-mentioned configuration, in the mobile communication system shown in FIG. 9, in addition to the existing voice communication called a circuit switching type in which communication paths are switched in an exchange and an inter-exchange network, there is realized an internet communication to be made through a packet transmission system (corresponding to the above-mentioned PDSN 105), which is called a packet switching type.
That is, voice data is transmitted between the PC 101a (101b)—the telephone network 108 by way of a path passing through the BTS 103, the BSC 104 and the LE/MSC 106, and packets are transmitted between the PC 101a (101b)—the internet 107 by way of a path passing through the BTS 103, the BSC 104 and the PDSN 105 as indicated by thick solid lines in FIG. 9.
Meanwhile, a feature of the packet data communication (which will hereinafter be referred to simply as “packet communication”) is burst-like data occurrence (requiring no real-time property), and a clear line is drawn between a case in which communication takes place (when data is transmitted from a station side to an individual mobile terminal or, conversely, when data is transmitted from a mobile terminal to a station side) and a case in which no communication takes place (when data is not transmitted from a station side to an individual mobile terminal or, conversely, when data is not transmitted from a mobile terminal to a station side). For this reason, although the connection is made between the MS 102a and the BS 134, there occurs a time in which packet (user data) transfer does not take place.
In addition, differing originally from a common 2W (way) telephone system, the mobile communication system described above is realized in a manner such that a plurality of MSs 102a share an air interface between the BS 134 and the MSs 102a and it is not designed such that the ruled MSs 102a can always establish the connection simultaneously (the concentration is made between the BS 134 and the MSs 102a). That is, limitation is imposed on the radio channel resource (which is a resource to be used for the radio communications in a radio zone between MS and BTS, for example, including predetermined radio frequency, diffusion code, time slot, memory, power of BTS, and others) (which will be referred to hereinafter as a “radio resource”).
Accordingly, in the case of the packet communications in a mobile communication system, in light of the behavior occurring when a user accesses the packet communication service (burst-like data occurrence forming a feature of the packet communication) and the desire on the effective utilization of the network side resource, the time in which the data transfer does not take place is allocated for the connection to the other users (MSs 102a), thereby achieving the effective utilization of the radio resource.
For realizing this, in the case of the packet communication in the mobile communication system, the standard defines an ACTIVE state and a DORMANT state as in-network call states peculiar to the packet communication.
In this case, for example, as illustratively shown in FIG. 10, the ACTIVE state signifies that “in a state where secured are all the communication resources between the MS 102a and the BS 134 needed for carrying out the packet communication service, in addition to the establishment of a connection A (radio channel), a logical connection B (PPP link) is established between the PC 101a connected to the MS 102a and the PDSN 105 and the transmission/reception is made between the PC 101a (101b) and the internet 107 on these connections A and B”.
On the other hand, the DORMANT state represents that “of the aforesaid connection A and the connection B, the connection A (radio channel) is placed into a released state while the connection B (PPP link) is in a maintained state”. That is, in the DORMANT state, the connection A is apparently made from the MS 102a to the PC 101a and from the BS 134 to the PDSN 105.
Therefore, when gaining the access from the PC 101a to the internet 107 through the use of the packet communication service, a user is not aware of the difference between the ACTIVE/DORMANT states forming the in-network call states. In this connection, one example of state transition of the ACTIVE/DORMANT states are mentioned hereinbelow.
(1) A user (subscriber) starts the access from the PC 101a (or 101b) to the internet 107.
(2) A user reads various home pages (WWW: World Wide Web) on the PC 101a (or 101b) [frequency occurrence of packets (traffic data): ACTIVE state].
(3) A user is carefully reading a given home page on the PC 101a (or 101b) (absence of traffic data).
(4) When the traffic data disappears due to the aforesaid (3), a timer starts in the MS 102a (or the SU 102b) or in the BS 134.
(5) Communication is made between the BS 134 and the MS 102a (or the SU 102b) at the time runout, thereby making the transition to the DORMANT state.
(6) A user is carefully reading a home page on the PC 101a (101b).
(7) In a case in which a user operates the PC 101a (or 101b) for reading a different home page, or when traffic data addressed to the PC 101a (101b) is sent from the internet 107 side to a user, a connection (connection A in FIG. 10) is established between the BS 134 and the MS 102a to set a state (ACTIVE state) in which the traffic data is transmittable/receivable.
Incidentally, the definitions of the ACTIVE state and the DORMANT state can depend upon the standard, and the distinction can also be made as a state in which the packet communication can be started through the use of the resource needed for the PPP link and secured by the radio resource securement.
Moreover, a user who is in the aforesaid ACTIVE state is referred to as an ACTIVE user, while a user who is in the DORMANT state is referred to as a DORMANT user. That is, the ACTIVE user denotes a user who actually accesses the packet communication service (user for which the radio resource is secured), while the DORMANT user depicts a user who once makes the packet communication as the ACTIVE user and then releases only the radio resource between the MS 102a (or 102b) and the BS 134 (the resource needed for a high-order PP link is maintained) at the elapse of a predetermined period of time after the packet transmission comes to an end.
In addition, in the mobile communication system, the upper limit of the number of simultaneous connections, i.e., the upper limit of the physical resources, is determined by the numbers of ACTIVE users and DORMANT users and is managed by the BSC 104. Therefore, whether a new packet communication call is established or not depends upon the number of ACTIVE users.
Concretely, when the number of ACTIVE users reaches the upper limit, since the communication resource for a new ACTIVE user does not exist, the present BSC 104 rejects a new call (new connection request) even if there exists a free DORMANT resource. For example, as shown in FIG. 11, assuming that each of the upper limits of numbers of ACTIVE users and DORMANT users is “30” (that is, users up to “60” can be accommodated), when a new connection request occurs in a state where the ACTIVE users reach the upper limit (“30”), the BSC 104 rejects this request though the DORMANT users do not reach the upper limit (“2” at present).
This is because a user is first required to become the ACTIVE user (a radio channel is allocated thereto) for becoming the DORMANT user and only the DORMANT user who has once been placed into the ACTIVE state can make the transition to the ACTIVE state through the re-securement of the radio resource.
For this reason, for example, as shown in FIG. 12, in a case in which the upper limit of number of ACTIVE users is “1” and the number of DORMANT users is equal to or more than 2, a terminal (PC) Y cannot start the packet communication except for making a connection request accidentally after the time T2 at the soonest, that is, after a terminal (PC) X already coming into the ACTIVE state through the authentication with the authentication service 171 of the ISP 170, which has been made in response to a dial-up connection request, shifts to the DORMANT state stemming from the fact that a state of no packet transmission/reception continues for a period of time T2 subsequently.
Accordingly, the maximum accommodation capacity of the packet communication initially estimated decreases and the occurrence of claims on the poor connections from the subscribers is expectable.
The present invention has been developed in consideration of these problems, and it is therefore an object of the invention to suppress the decrease in subscriber accommodation capacity of the packet communication in a manner such that, even if the number of ACTIVE users reaches the upper limit, when a free MS shiftable to the DORMANT state (allowable MS within the limitation on resource such as PPP connection resource) exists, new call connection processing is conducted through the use of a PPP connection resource already secured by the acquisition of at least a radio resource, or the like, for accommodating a new user as a DORMANT user which is in an immediately packet-communicable state.